This relates generally to imaging systems, and more particularly, to imaging systems with stacked-chip image sensors.
Image sensors are commonly used in imaging systems such as cellular telephones, cameras, and computers to capture images. In a typical arrangement, an image sensor is provided with an array of image sensor pixels and control circuitry for operating the image sensor pixels. In a conventional imaging system the control circuitry is laterally separated from the image sensor pixels on a silicon semiconductor substrate. Each row of image sensor pixels typically communicates with the control circuitry along a common metal line on the silicon semiconductor substrate. Similarly, each column of image sensor pixels communicates with the control circuitry along a common metal line.
In this type of system, the rate at which image pixel data can be read out from the image sensor pixels and the rate at which control signals can be supplied to the image sensor pixels can be limited by the use of the shared column and row lines. This type of limitation can limit the rate at which image frames may be captured. Transient image signals such as image light from flashing light sources or from moving objects may be improperly represented in image data due to the limited frame rate.
Conventional image sensors capture images using a predetermined integration (exposure) time. When capturing images from real-world scenes using conventional image sensors, images captured from scenes having low light conditions can have insufficient signal-to-noise ratio and images captured from scenes with moving objects can include motion artifacts such as motion blur.
It would therefore be desirable to be able to provide improved imaging systems with enhanced image capture and processing efficiency.